Composite polymer electrolyte membrane decorated with porous titanium oxide nanotubes for fuel cell operating under low relative humidity

Sulfonated Polysulfone/TiO2(B) Nanowires Composite Membranes as Polymer Electrolytes in Fuel Cells

New proton conducting membranes based on sulfonated polysulfone (sPSU) reinforced with TiO₂(B) nanowires (1, 2, 5 and 10 wt.%) were synthesized and characterized. TiO₂(B) nanowires were synthesized by means of a hydrothermal method by mixing TiO₂ precursor in aqueous solution of NaOH as solvent. The presence of the TiO₂(B) nanowires into the polymer were confirmed by means of Field Emission Scanning Electron Microscopy, Fourier transform infrared and X-ray diffraction. The thermal study showed an increase of almost 20 °C in the maximum temperature of sPSU backbone decomposition due to the presence of 10 wt.% TiO₂(B) nanowires. Water uptake also is improved with the presence of hydrophilic TiO₂(B) nanowires. Proton conductivity of sPSU with 10 wt.% TiO₂(B) nanowires was 21 mS cm⁻¹ (at 85 °C and 100% RH). Under these experimental conditions the power density was 350 mW cm⁻² similar to the value obtained for Nafion 117. Considering all these obtained results, the composite membrane doped with 10 wt.% TiO₂(B) nanowires is a promising candidate as proton exchange electrolyte in fuel cells (PEMFCs), especially those operating at high temperatures.